| /* |
| * Copyright 2007 ZXing authors |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package com.google.zxing.common; |
| |
| import java.util.Arrays; |
| |
| /** |
| * <p>A simple, fast array of bits, represented compactly by an array of ints internally.</p> |
| * |
| * @author Sean Owen |
| */ |
| public final class BitArray implements Cloneable { |
| |
| private int[] bits; |
| private int size; |
| |
| public BitArray() { |
| this.size = 0; |
| this.bits = new int[1]; |
| } |
| |
| public BitArray(int size) { |
| this.size = size; |
| this.bits = makeArray(size); |
| } |
| |
| // For testing only |
| BitArray(int[] bits, int size) { |
| this.bits = bits; |
| this.size = size; |
| } |
| |
| public int getSize() { |
| return size; |
| } |
| |
| public int getSizeInBytes() { |
| return (size + 7) / 8; |
| } |
| |
| private void ensureCapacity(int size) { |
| if (size > bits.length * 32) { |
| int[] newBits = makeArray(size); |
| System.arraycopy(bits, 0, newBits, 0, bits.length); |
| this.bits = newBits; |
| } |
| } |
| |
| /** |
| * @param i bit to get |
| * @return true iff bit i is set |
| */ |
| public boolean get(int i) { |
| return (bits[i / 32] & (1 << (i & 0x1F))) != 0; |
| } |
| |
| /** |
| * Sets bit i. |
| * |
| * @param i bit to set |
| */ |
| public void set(int i) { |
| bits[i / 32] |= 1 << (i & 0x1F); |
| } |
| |
| /** |
| * Flips bit i. |
| * |
| * @param i bit to set |
| */ |
| public void flip(int i) { |
| bits[i / 32] ^= 1 << (i & 0x1F); |
| } |
| |
| /** |
| * @param from first bit to check |
| * @return index of first bit that is set, starting from the given index, or size if none are set |
| * at or beyond this given index |
| * @see #getNextUnset(int) |
| */ |
| public int getNextSet(int from) { |
| if (from >= size) { |
| return size; |
| } |
| int bitsOffset = from / 32; |
| int currentBits = bits[bitsOffset]; |
| // mask off lesser bits first |
| currentBits &= -(1 << (from & 0x1F)); |
| while (currentBits == 0) { |
| if (++bitsOffset == bits.length) { |
| return size; |
| } |
| currentBits = bits[bitsOffset]; |
| } |
| int result = (bitsOffset * 32) + Integer.numberOfTrailingZeros(currentBits); |
| return result > size ? size : result; |
| } |
| |
| /** |
| * @param from index to start looking for unset bit |
| * @return index of next unset bit, or {@code size} if none are unset until the end |
| * @see #getNextSet(int) |
| */ |
| public int getNextUnset(int from) { |
| if (from >= size) { |
| return size; |
| } |
| int bitsOffset = from / 32; |
| int currentBits = ~bits[bitsOffset]; |
| // mask off lesser bits first |
| currentBits &= -(1 << (from & 0x1F)); |
| while (currentBits == 0) { |
| if (++bitsOffset == bits.length) { |
| return size; |
| } |
| currentBits = ~bits[bitsOffset]; |
| } |
| int result = (bitsOffset * 32) + Integer.numberOfTrailingZeros(currentBits); |
| return result > size ? size : result; |
| } |
| |
| /** |
| * Sets a block of 32 bits, starting at bit i. |
| * |
| * @param i first bit to set |
| * @param newBits the new value of the next 32 bits. Note again that the least-significant bit |
| * corresponds to bit i, the next-least-significant to i+1, and so on. |
| */ |
| public void setBulk(int i, int newBits) { |
| bits[i / 32] = newBits; |
| } |
| |
| /** |
| * Sets a range of bits. |
| * |
| * @param start start of range, inclusive. |
| * @param end end of range, exclusive |
| */ |
| public void setRange(int start, int end) { |
| if (end < start || start < 0 || end > size) { |
| throw new IllegalArgumentException(); |
| } |
| if (end == start) { |
| return; |
| } |
| end--; // will be easier to treat this as the last actually set bit -- inclusive |
| int firstInt = start / 32; |
| int lastInt = end / 32; |
| for (int i = firstInt; i <= lastInt; i++) { |
| int firstBit = i > firstInt ? 0 : start & 0x1F; |
| int lastBit = i < lastInt ? 31 : end & 0x1F; |
| // Ones from firstBit to lastBit, inclusive |
| int mask = (2 << lastBit) - (1 << firstBit); |
| bits[i] |= mask; |
| } |
| } |
| |
| /** |
| * Clears all bits (sets to false). |
| */ |
| public void clear() { |
| int max = bits.length; |
| for (int i = 0; i < max; i++) { |
| bits[i] = 0; |
| } |
| } |
| |
| /** |
| * Efficient method to check if a range of bits is set, or not set. |
| * |
| * @param start start of range, inclusive. |
| * @param end end of range, exclusive |
| * @param value if true, checks that bits in range are set, otherwise checks that they are not set |
| * @return true iff all bits are set or not set in range, according to value argument |
| * @throws IllegalArgumentException if end is less than start or the range is not contained in the array |
| */ |
| public boolean isRange(int start, int end, boolean value) { |
| if (end < start || start < 0 || end > size) { |
| throw new IllegalArgumentException(); |
| } |
| if (end == start) { |
| return true; // empty range matches |
| } |
| end--; // will be easier to treat this as the last actually set bit -- inclusive |
| int firstInt = start / 32; |
| int lastInt = end / 32; |
| for (int i = firstInt; i <= lastInt; i++) { |
| int firstBit = i > firstInt ? 0 : start & 0x1F; |
| int lastBit = i < lastInt ? 31 : end & 0x1F; |
| // Ones from firstBit to lastBit, inclusive |
| int mask = (2 << lastBit) - (1 << firstBit); |
| |
| // Return false if we're looking for 1s and the masked bits[i] isn't all 1s (that is, |
| // equals the mask, or we're looking for 0s and the masked portion is not all 0s |
| if ((bits[i] & mask) != (value ? mask : 0)) { |
| return false; |
| } |
| } |
| return true; |
| } |
| |
| public void appendBit(boolean bit) { |
| ensureCapacity(size + 1); |
| if (bit) { |
| bits[size / 32] |= 1 << (size & 0x1F); |
| } |
| size++; |
| } |
| |
| /** |
| * Appends the least-significant bits, from value, in order from most-significant to |
| * least-significant. For example, appending 6 bits from 0x000001E will append the bits |
| * 0, 1, 1, 1, 1, 0 in that order. |
| * |
| * @param value {@code int} containing bits to append |
| * @param numBits bits from value to append |
| */ |
| public void appendBits(int value, int numBits) { |
| if (numBits < 0 || numBits > 32) { |
| throw new IllegalArgumentException("Num bits must be between 0 and 32"); |
| } |
| ensureCapacity(size + numBits); |
| for (int numBitsLeft = numBits; numBitsLeft > 0; numBitsLeft--) { |
| appendBit(((value >> (numBitsLeft - 1)) & 0x01) == 1); |
| } |
| } |
| |
| public void appendBitArray(BitArray other) { |
| int otherSize = other.size; |
| ensureCapacity(size + otherSize); |
| for (int i = 0; i < otherSize; i++) { |
| appendBit(other.get(i)); |
| } |
| } |
| |
| public void xor(BitArray other) { |
| if (size != other.size) { |
| throw new IllegalArgumentException("Sizes don't match"); |
| } |
| for (int i = 0; i < bits.length; i++) { |
| // The last int could be incomplete (i.e. not have 32 bits in |
| // it) but there is no problem since 0 XOR 0 == 0. |
| bits[i] ^= other.bits[i]; |
| } |
| } |
| |
| /** |
| * |
| * @param bitOffset first bit to start writing |
| * @param array array to write into. Bytes are written most-significant byte first. This is the opposite |
| * of the internal representation, which is exposed by {@link #getBitArray()} |
| * @param offset position in array to start writing |
| * @param numBytes how many bytes to write |
| */ |
| public void toBytes(int bitOffset, byte[] array, int offset, int numBytes) { |
| for (int i = 0; i < numBytes; i++) { |
| int theByte = 0; |
| for (int j = 0; j < 8; j++) { |
| if (get(bitOffset)) { |
| theByte |= 1 << (7 - j); |
| } |
| bitOffset++; |
| } |
| array[offset + i] = (byte) theByte; |
| } |
| } |
| |
| /** |
| * @return underlying array of ints. The first element holds the first 32 bits, and the least |
| * significant bit is bit 0. |
| */ |
| public int[] getBitArray() { |
| return bits; |
| } |
| |
| /** |
| * Reverses all bits in the array. |
| */ |
| public void reverse() { |
| int[] newBits = new int[bits.length]; |
| // reverse all int's first |
| int len = (size - 1) / 32; |
| int oldBitsLen = len + 1; |
| for (int i = 0; i < oldBitsLen; i++) { |
| long x = bits[i]; |
| x = ((x >> 1) & 0x55555555L) | ((x & 0x55555555L) << 1); |
| x = ((x >> 2) & 0x33333333L) | ((x & 0x33333333L) << 2); |
| x = ((x >> 4) & 0x0f0f0f0fL) | ((x & 0x0f0f0f0fL) << 4); |
| x = ((x >> 8) & 0x00ff00ffL) | ((x & 0x00ff00ffL) << 8); |
| x = ((x >> 16) & 0x0000ffffL) | ((x & 0x0000ffffL) << 16); |
| newBits[len - i] = (int) x; |
| } |
| // now correct the int's if the bit size isn't a multiple of 32 |
| if (size != oldBitsLen * 32) { |
| int leftOffset = oldBitsLen * 32 - size; |
| int currentInt = newBits[0] >>> leftOffset; |
| for (int i = 1; i < oldBitsLen; i++) { |
| int nextInt = newBits[i]; |
| currentInt |= nextInt << (32 - leftOffset); |
| newBits[i - 1] = currentInt; |
| currentInt = nextInt >>> leftOffset; |
| } |
| newBits[oldBitsLen - 1] = currentInt; |
| } |
| bits = newBits; |
| } |
| |
| private static int[] makeArray(int size) { |
| return new int[(size + 31) / 32]; |
| } |
| |
| @Override |
| public boolean equals(Object o) { |
| if (!(o instanceof BitArray)) { |
| return false; |
| } |
| BitArray other = (BitArray) o; |
| return size == other.size && Arrays.equals(bits, other.bits); |
| } |
| |
| @Override |
| public int hashCode() { |
| return 31 * size + Arrays.hashCode(bits); |
| } |
| |
| @Override |
| public String toString() { |
| StringBuilder result = new StringBuilder(size + (size / 8) + 1); |
| for (int i = 0; i < size; i++) { |
| if ((i & 0x07) == 0) { |
| result.append(' '); |
| } |
| result.append(get(i) ? 'X' : '.'); |
| } |
| return result.toString(); |
| } |
| |
| @Override |
| public BitArray clone() { |
| return new BitArray(bits.clone(), size); |
| } |
| |
| } |